Mechanisms of hypoxia induced exacerbation of cerebral cavernous malformations

脑海绵状血管畸形（CerebralCavernousMalformations，CCM）是一种常见的由内皮细胞簇构成的神经血管病变 充满了被胶质增生包围的血液CCM影响约1/200的儿童和成人，导致终身风险 出血性中风和神经功能缺损，目前没有有效的药物治疗。损失 CCM三个基因的功能突变推动脑血管病变。然而，CCM的倾向 相对于其他组织，中枢神经系统（CNS）实质中形成的损伤尚未完全被确定。 疾病严重程度的异质性表明，环境或生物因素（例如， 基因、神经细胞）作为疾病调节剂。我们和其他人已经证明， 内皮生长因子（VEGF）信号传导和相关的血管渗漏是CCM的重要贡献者 疾病我们的初步数据表明，缺氧条件有助于积极的发病和发展 CCM疾病。我们观察到缺氧通过加剧CCM疾病的数量而作为CCM疾病的加速剂 CCM动物模型中脑血管病变的大小。我们还观察到小鼠和人CCM组织 导致缺氧诱导因子1 α（HIF-1a）活性增加， CCM发病机制。拟议的研究将检验缺氧通过以下途径加剧CCM的假设： 缺氧程序从星形胶质细胞和内皮细胞，导致异常的血管发育和中风， 颅内出血此外，我们假设间歇性缺氧（发生在患有 阻塞性睡眠呼吸暂停）将进一步加剧CCM。具体目标1将检验缺氧 通过升高小鼠CCM中星形胶质细胞中缺氧驱动的基因而加剧CCM形成。我们将 研究缺氧对星形胶质细胞基因表达的影响（例如，低氧程序，VEGF） 在存在或不存在EGFP的情况下，从星形胶质细胞中纯化EGFP标记的核糖体获得翻译的mRNA， 无CCM病变。将使用体外共培养模型来确定CCM之间的相互作用 血管内皮细胞和星形胶质细胞，导致血管功能障碍。具体目标2将检验以下假设： 缺氧通过HIF-1a蛋白稳定小鼠脑内皮细胞促进CCM形成 CCM.我们将研究内皮细胞HIF-1a在内皮屏障功能、基因表达和细胞凋亡中的作用。 使用CCM小鼠模型的VEGF表达、VEGF信号传导。具体目标3将检验以下假设： 间歇性低氧加重小鼠CCM。我们将研究间歇性缺氧驱动的CCM的作用， 病变负荷，使用间歇性缺氧条件下的CCM小鼠模型，部分重现夜间 阻塞性睡眠呼吸暂停综合征（OSA）患者的血氧水平。这项研究可能会带来一种新的 治疗方法（例如，用于活化的星形胶质细胞和CCM内皮的组合疗法）和 通过定义环境（例如，高海拔）或病理因素（例如，OSA， 慢性肺部疾病），改变氧气水平可能会作为风险因素，为患者的CCM影响。

Cerebral Cavernous Malformations (CCMs) are common neurovascular lesions made of endothelium clusters filled with blood surrounded by gliosis. CCMs affect ~1/200 children and adults, causing a lifetime risk of hemorrhagic strokes and neurologic deficits for which there is no current effective pharmacologic therapy. Loss of function mutations in three CCM genes propels brain vascular changes. However, the propensity of CCM lesions to form in the central nervous system (CNS) parenchyma relative to other tissues has not been fully explained, and the heterogeneity in disease severity suggests that environmental or biological factors (e.g. other genes, neural cells) act as disease modifiers. We and others have demonstrated that increased vascular endothelial growth factor (VEGF) signaling and associated vascular leakage are significant contributors to CCM disease. Our preliminary data show that hypoxic conditions contribute to an aggressive onset and progression of CCM disease. We observed that hypoxia acts as an accelerant of CCM disease by exacerbating the number and size of brain vascular lesions in CCM animal models. We also observed that mouse and human CCM tissue results in increased hypoxia-inducible factor 1 alpha (HIF-1a) activity, and that proliferative astrocytes influence CCM pathogenesis. The proposed study will test the hypothesis that hypoxia exacerbates CCMs through hypoxic programs from astrocytes and endothelium, leading to abnormal vascular development and stroke due to intracranial hemorrhage. Moreover, we hypothesize that intermittent hypoxia (that occurs with patients with obstructive sleep apnea) will further exacerbate CCMs. Specific Aim 1 will test the hypothesis that hypoxia exacerbates CCM formation by elevating hypoxia-driven genes in astrocytes in murine CCM. We will investigate the effect of hypoxia on astrocyte gene expression (e.g., hypoxic program, VEGF) by profiling translated mRNAs obtained from the purification of the EGFP-tagged ribosome in astrocytes in the presence or absence of CCM lesions. Co-culture in vitro models will be used to define the interaction between CCM endothelium and astrocytes that propels vascular dysfunction. Specific Aim 2 will test the hypothesis that hypoxia exacerbates CCM formation by HIF-1a protein stabilization in the brain endothelium in murine CCM. We will investigate the role of endothelial HIF-1a on changes in the endothelial barrier function, gene expression, VEGF signaling using CCM mouse models. Specific Aim 3 will test the hypothesis that intermittent hypoxia exacerbates murine CCM. We will investigate the role of intermittent hypoxia-driven CCM lesion burden, using mouse models of CCM under intermittent hypoxia that partially recapitulates nocturnal oxygen profile in patients with obstructive sleep apnea (OSA). The proposed research may lead to a new therapeutic approach (e.g., combination therapies for activated astrocytes and CCM endothelium) and preventive measures by defining how environmental (e.g., high altitude) or pathological factors (e.g., OSA, chronic lung disease) that alter oxygen levels may act as risk factors for patients affected with CCMs.